SE2050249A1

SE2050249A1 - A throttle control mechanism for a surfacing machine

Info

Publication number: SE2050249A1
Application number: SE2050249A
Authority: SE
Inventors: Andreas Fogelberg
Original assignee: Husqvarna Ab
Priority date: 2020-03-05
Filing date: 2020-03-05
Publication date: 2021-09-06
Also published as: WO2021177872A1; SE544026C2; US20230152838A1; CA3170433A1; US11860663B2

Abstract

A throttle control mechanism for a surfacing machine,the control mechanism comprising a control member (310) arranged movable (M, D) in a support structure (320),wherein the control member (310) is arranged to be tensely attached to a throttle actuator (330) of the surfacing machine via a tensile engagement member (340),wherein the control member (310) is arranged to be held fixed in the support structure in at least a first throttle position (350), where the control member is arranged biased towards an idle throttle position (370) when released from the first throttle position (350), andwherein the first throttle position (350) and the idle throttle position (370) are configurable to provide an engine speed margin with respect to a clutch engagement engine speed range of the surfacing machine.

Description

TITLE A throttle control mechanism for a surfacing machine TECHNICAL FIELD The present disclosure relates to surfacing machines, i.e., grinding andpolishing machines for treating hard surfaces such as concrete and stonefloors and other surfaces. There are disclosed throttle control mechanisms,i.e., arrangements for controlling an engine speed of the surfacing machine.

BACKGROUND Floor grinding relates to the process of smoothing and polishing, e.g., concretefloors by means of a grinding machine. By grinding and polishing hardmaterials such as concrete and stone, it is possible to achieve a finishresembling that of a polished marble floor. A polished concrete floor is easy toclean and is also often visually appealing.

Floor grinding may also be used to level a floor surface, i.e., to remove bumpsand other imperfections. This may be desired in production facilities wherecomplicated machinery may require a levelled supporting surface.

Floor grinders may be powered by combustion engines such as gasolineengines or propane powered engines. Such engines are normally connected to the rotatable work tool via a clutch arrangement.

Known clutch arrangements comprise, e.g., friction disc clutches andcentrifugal clutches.

A problem with many clutch arrangements is clutch slippage which happenswhen the clutch does not engage properly. This slippage generates frictionalheat which may damage the clutch arrangement permanently.

There is a need for cost effective and efficient arrangements for operating asurfacing machine to prevents clutch slippage.

SUMMARY lt is an object of the present disclosure to provide improved mechanisms forthrottle control of surfacing machines, this object is at least in part obtained bya throttle control mechanism for a surfacing machine. The control mechanismcomprises a control member arranged movable in a support structure, whereinthe control member is arranged to be tensely attached to a throttle actuator ofthe surfacing machine via a tensile engagement member. The control memberis arranged to be held fixed in the support structure in at least a first throttleposition, where the control member is arranged biased towards an idle throttleposition when released from the first throttle position. The first throttle positionand the idle throttle position are configurable to provide an engine speedmargin with respect to an undesired engine speed range of the surfacingmachine. This throttle control mechanism dissuades a machine operator fromoperating a machine such as a surfacing machine in an undesired enginespeed range, at least for a prolonged period of time. The operator is able toselect at least one distinct throttle position, which position can be adjusteddepending on type of machine and operating condition. Thus, the machine lifemay be prolonged, and a surfacing operation can be made more efficient. Thethrottle control mechanisms disclosed herein are robust and durable and at the same time possible to realize at low cost.

According to aspects, the control member is arranged to be held fixed in thesupport structure at a second throttle position different from the first throttleposition. The second throttle position is configurable to provide a further enginespeed margin with respect to the undesired engine speed range. Thus, theoperator may select from one out of a plurality of throttle settings. One settingmay, e.g., be associated with a low engine speed suitable for some operations,while the other setting may be associated with a high engine speed suitable for some other operations.

According to aspects, the throttle control comprises a resilient biasing memberand the control member is arranged biased towards the idle throttle position by the resilient biasing member. The resilient biasing member may, e.g., comprise a primary extension spring configured to pull the control membertowards the idle throttle position. The resilient biasing member may alsocomprise a secondary extension spring configured to pull the control membertowards the idle throttle position, wherein the secondary extension spring isarranged with a higher spring constant compared to the primary extensionspring. This way a robust yet low cost biasing function is obtained. The biasingforce can be adjusted by selecting various types of springs, providing a rangeof design options. The secondary extension spring improves on the locking feature of the control member, which will be explained in more detail below.

According to aspects, the tensile engagement member is at least partly madefrom a resilient material, thereby biasing the control member towards the idlethrottle position. Using a resilient material such as rubber cord or the like in thetensile engagement member provides an effect similar to that of the secondary extension spring.

According to aspects, the tensile engagement member comprises anadjustment screw configured to adjust a tension associated with the tensileengagement member. Thus, similar to the adjustment process for a bicyclehandbrake, the throttle level corresponding to the various throttle positions canbe adjusted or fine-tuned to a desired level in an efficient and convenient manner.

According to aspects, the support structure comprises a sleeve, and thecontrol member is arranged inside the sleeve to slide along the extensiondirection of the sleeve. This way an operator may simply operate the controlmember by pulling on a knob or handle of the control member. Thisarrangement is not prone to accidentally changing engine speed by, e.g.,inadvertently operating the control member. The sleeve arrangement is alsoresilient to dust and debris, which may othenNise interfere with the control member action.

According to aspects, the sleeve comprises a slide bearing configured toslidably support the control member inside the sleeve. The slide bearingreduces friction inside the sleeve, and also supports the control member to provide a throttle control mechanism with high quality feel which is easy to operate.

According to aspects, the sleeve comprises a main extending in the extensiondirection of the sleeve, and the control member comprises a guiding pinarranged to be guided by the main groove in the eiongation direction of thesleeve. The control member is rotatably supported in the sleeve to move theguiding pin transversal to the elongation direction away from the main grooveand into a locking position. This type of control mechanism is intuitive tooperate, mechanically durable, and also resilient to build-up of particulatematter which may othenNise interfere with the control member. There is littlerisk of the control member inadvertently slipping out from a throttle position.

According to aspects, the control member comprises one or morecircumferentially formed grooves transversally formed with respect to aneiongation direction of the control member. The support structure comprises alocking pin arranged biased to enter the one or more circumferentially formedgrooves, thereby fixing the control member in at least the first throttle position.This arrangement provides an alternative to the arrangement based ongrooves and guiding pin. lf the circumferential grooves are designed withtapered edges, and the biasing force of the locking pin is matched to the restof the structure, then the control member can be operated by a single hand toovercome the fixing force exerted by the locking pin, which is an advantage.The design can also be adjusted to require two-handed operation, which may be warranted in order to prevent inadvertently operating the control member.

According to aspects, the throttle control mechanism comprises a dead-manswitch arrangement with a line or cord attached to the locking pin. This line orcord can, e.g., be attached to an operator. lf this operator falls or is injured,then the dead-man switch is activated to bring the surfacing machine into theidle throttle position. The dead-man switch can also be attached to, e.g., avacuum device or other peripheral unit, thus ensuring that the peripheral unit is always near the surfacing machine.

According to aspects, the resilient biasing member comprises a compressionspring configured to push the control member towards the idle throttle position.The compression spring may, e.g., be comprised in the support structure, where it is protected from dust and debris.

According to aspects, the control member comprises a handle pivotablyarranged in the support structure. The handle provides an alternative to thedesigns comprising a control member arranged slidably inside a sleevestructure.

There are also disclosed herein floor grinders and construction equipmentcomprising the throttle control mechanisms and thus associated with theadvantages mentioned above.

Generally, all terms used in the claims are to be interpreted according to theirordinary meaning in the technical field, unless explicitly defined otherwiseherein. All references to "a/an/the element, apparatus, component, means,step, etc." are to be interpreted openly as referring to at least one instance ofthe element, apparatus, component, means, step, etc., unless explicitly statedotherwise. The steps of any method disclosed herein do not have to beperformed in the exact order disclosed, unless explicitly stated. Furtherfeatures of, and advantages with, the present invention will become apparentwhen studying the appended claims and the following description. The skilledperson realizes that different features of the present invention may becombined to create embodiments other than those described in the following,without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure will now be described in more detail with reference to the appended drawings, whereFigure 1 shows an example surfacing machine;Figure 2 schematically illustrates a clutch arrangement; Figures 3A-E illustrates an example throttle control mechanism; Figures 4-6 illustrate details of example throttle control mechanism; Figures 7A-D illustrate an example throttle control mechanism; DETAILED DESCRIPTION The invention will now be described more fully hereinafter with reference to theaccompanying drawings, in which certain aspects of the invention are shown.This invention may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments and aspects set forth herein;rather, these embodiments are provided by way of example so that thisdisclosure will be thorough and complete, and will fully convey the scope ofthe invention to those skilled in the art. Like numbers refer to like elementsthroughout the description. lt is to be understood that the present invention is not limited to theembodiments described herein and illustrated in the drawings; rather, theskilled person will recognize that many changes and modifications may bemade within the scope of the appended claims.

Figure 1 illustrates a surfacing machine 100. The grinding portion 110 of thesurfacing machine 100 is powered by a combustion engine 120 such as agasoline powered engine or a propane powered engine. The mechanismwhich controls the engine speed is herein referred to as a throttle mechanism.lt is normally desired to be able to control the engine speed in dependence ofgrinding scenario and grinding tool. Some operating conditions require higherengine speeds while other conditions require lower engine speeds. Engine speed is normally measured in revolutions per minute (rpm).

Figure 2 schematically illustrates a transmission system for transferring torqueT from the engine 210 to the grinding portion 230. A clutch mechanism 220 isarranged in-betvveen the engine 210 and the grinding portion 230. This clutchmechanism may, e.g., be a centrifugal clutch mechanism or a friction discclutch mechanism. Such clutch mechanisms are known and will not be discussed in more detail herein.

A problem with many clutch mechanisms is that the clutch normally has anengagement range where the clutch is only partly engaged to transfer thetorque T. ln this case the clutch may slip, which generates heat due to thefriction in the clutch. For a centrifugal clutch, the engagement range for asurfacing machine is normally somewhere around 1800 to 2800 rpm. lf theengine speed is maintained in this undesired engine speed range, then enoughheat may be generated in the clutch to cause permanent damage to the clutch.

The techniques disclosed herein are not only applicable to floor surfacingmachines, such as that exemplified in Figure 1. The throttle controlmechanisms disclosed herein can be applied with advantage in a wide rangeofdifferent machines comprising combustion engines and clutch mechanisms.Some examples where the throttle mechanisms may be applied comprise coredrilling equipment, lawn movers, floor cleaning and sweeping equipment, compactors, floor saws, vacuum cleaners and the like.

Further, some combustion engines have scavenging systems which areoptimized for particular driving conditions. The ideal driving condition is usuallyassociated with full engine load and wide-open throttle (WOT). When operatingthe engine at the ideal driving condition, the scavenging system is effective,meaning that the engine delivers high power with low emissions. Engines ofthe type used for floor surfacing machines are often not configured for varyingdriving conditions. Thus, when departing from the ideal driving condition thescavenging system ceases to be effective, which can lead to unwanted effectssuch as misfiring, increased emission levels, and high temperatures on engineparts such as cylinder, piston, crankcase and muffler. By running thecombustion engine for extended time periods far from the ideal drivingcondition the engine may even break down. During an idle mode drivingcondition, i.e., when the user-operated throttle is almost closed, thescavenging system will be far from optimal. However, the effects on thecombustion engine from sub-optimal scavenging operation during low idle isoften not very harmful due to the low engine speeds involved. Thus, there isnormally an undesired engine speed range associated with combustion engines for surfacing machines.

According to some aspects, the undesired engine speed range may beexpressed in terms of a clutch engagement speed. For instance, the idlethrottle position may be associated with an engine speed below 90% of theclutch engagement speed. The first throttle position corresponding to a lowspeed setting may be associated with an engine speed around 110% of theclutch engagement speed. lt is appreciated that these engine speed thresholdsare dependent on the equipment and use case.

A problem with some surfacing machines is that the operator is able tomaintain engine speed in an undesired engine speed range for prolongedperiods of time, such as within the clutch engagement range or within anengine speed range where the scavenging operation of the combustion engineis not effective enough. lt is desired to dissuade an operator from operating the surfacing machine in such undesired engine speed ranges.

An object of the present disclosure is to provide a throttle control mechanismwhich acts to dissuade operation in an undesired engine speed range. This isaccomplished by means of a throttle control mechanism which has one or moredistinct throttle positions which can be selected by the operator and which areconfigured with a margin from the undesired engine speed range. The throttlecontrol mechanism is then biased towards an idle position such that, when thecontrol member of the throttle is released from a throttle position, the controlmember of the throttle mechanism automatically reverts back to the idle throttleposition, quickly passing the undesired engine speed range. Thus, a machineoperator is dissuaded from prolonged operation in the undesired engine speedrange, since maintaining operation in the undesired engine speed range willbe uncomfortable and/or will result in an awkward work position for the operator.

Figures 3-7 provide some non-limiting examples of how this type of throttlecontrol mechanism may be realized. Many aspects of the different examplescan be combined, as the skilled person realizes from considering the detaileddrawings. All throttle control mechanisms disclosed herein are suitable for asurfacing machine such as that shown in Figure 1. However, the throttle control mechanisms may also be applied to other types of machinery which areassociated with an undesired engine speed range.

Figures 3-7 show examples of a throttle control mechanism 300, 400, 500,600, 700 for a surfacing machine such as the surfacing machine 100 discussedin connection to Figure 1. The control mechanism comprises a control member310, 410, 510, 610, 710 arranged movable M, D in a support structure 320,420, 520, 620, 720. The support structure can, e.g., be a sleeve 320, 420, 520,620 as illustrated in Figures 3-6, where the control member 310, 410, 510, 610is arranged inside the sleeve to slide along an extension direction E of thesleeve. The support structure can also be in the form of a lever housingstructure 720 as illustrated in Figure 7. The operator controls engine speed viathe control member. For the mechanisms 300, 400, 500 in Figures 3-5, theoperator pulls the control member 310, 410, 510 out from the sleeve in orderto increase engine speed. The control member may comprise a knob 311, 411,511, 611 for this purpose. ln Figure 6 the control member 610 is insteadpushed into the sleeve to increase engine speed, while the mechanismillustrated in Figures 7A-D is a lever mechanism with a pivotable controlmember 710.

The control member 310, 410, 510, 610, 710 is generally arranged to betensely attached to a throttle actuator 330, 430, 530, 630 of the surfacingmachine 100 via a tensile engagement member 340, 440, 540, 640, 740. Atensile engagement member is an engagement member which is arranged toexert a pulling force, i.e., a tensile force, on a throttle actuator 330, 430, 530,630 associated with the combustion engine to be controlled. Some of thetensile engagement members disclosed herein are also arranged to exert apushing force on the throttle actuator. However, some of the implementationsdisclosed herein, such as the implementations 400, 500, can be used with anon-rigid engagement member, such as a cord. Other implementations, suchas that in Figures 3A-E and that in Figures 6-7 use a rigid tensile engagement member such as a wire or rod.

The control member 310, 410, 510, 610, 710 is arranged to be held fixed inthe support structure in at least a first throttle position 350, 450, 750. Thus, thecontrol member can be used by the operator to set a desired throttle level of the machine. ln order to avoid operation in the undesired engine speed range discussedabove, the control member is arranged biased towards an idle throttle position370, 470, 770 when released from the first throttle position 350, 450, 750. Thefirst throttle position 350, 450, 750 and the idle throttle position 370, 470, 770are configurable to provide an engine speed margin with respect to anundesired engine speed range of the surfacing machine 100. This means thatboth the idle throttle position and the first throttle position correspond to enginespeeds which are sufficiently removed from the undesired operating range. Asnoted above, this undesired engine speed range may be a clutch engagementengine speed range and/or an engine speed range where the scavengingoperation of the combustion engine is not effective.

To operate the throttle control mechanism, an operator releases the controlmember from a current throttle position, and moves the control member into adesired throttle position, such as the first throttle position, whereby the controlmember is held fixed in the desired throttle position by the support structure. lfthe operator lets go of the control member before the control member has beenproperly received in the desired throttle position, the control memberautomatically reverts back to the idle throttle position.

According to some aspects, the first throttle position 350, 450, 750 is a lowspeed throttle position configured to provide an engine speed between 2800 rpm and 3200 rpm, and preferably around 3000 rpm.

According to some aspects, the control member 310, 410, 510, 610, 710 isarranged to be held fixed in the support structure 320, 420, 520, 620, 720 alsoat a second throttle position 360, 460, 760. The second throttle position 360,460, 760 is configurable to provide a further engine speed margin with respectto the undesired engine speed range. This way the machine operator mayconfigure the engine speed at two different settings, such as a high speed setting and a low speed setting, in addition to the idle speed setting. Both thelow speed setting and the high speed setting are sufficiently removed from theundesired engine speed range. Of course, more than two distinct engine speedsettings may be provided by adding more than two configurable throttlepositions to the throttle control mechanism 300, 400, 500, 600, 700.

According to some aspects, the second throttle position 360, 460, 760 is a highspeed throttle position configured to provide an engine speed between 3300rpm and 3700 rpm, and preferably around 3500 rpm. ln order for the control member to strive towards the idle position, the throttlecontrol mechanism 300, 400, 500, 600, 700 comprises a resi|ient biasingmember 380, 480, 580, 680. The control member 310, 410, 510, 610, 710 isthen arranged biased towards the idle throttle position 370, 470, 770 by the resi|ient biasing member.

With reference to Figures 3A-E, and Figure 4, the resi|ient biasing membermay for instance comprise a primary extension spring 380, 480 configured topull the control member 310, 410 towards the idle throttle position 370, 470.The control member 310, 410 may be pulled out from the support structure bythe operator in order to increase engine speed. By pulling the control memberout the primary extension spring 380, 480 is extended and therefore generatesa counter-force which strives to pull the control member back into the sleeve320, 420. The idle position 370 of the control member is the position where thecontrol member is fully retracted into the sleeve.

The throttle actuator 330, 430, 530, 630 of the surfacing machine 100 mayoptionally be biased into the idle position by a resi|ient member such as atorsion spring or the like. This torsion spring may constitute the resi|ient biasingmember. Thus, by pulling the control member out the torsion spring generatesa counter-force which strives to pull the control member back to the idle throttleposition, e.g., into the sleeve.

The throttle control mechanism 300 shown in Figure 3 is akin to a bayonetconnector. The control member 310 is cylindrically shaped to fit inside a tubularsleeve 320. The sleeve optionally comprises a slide bearing 376 configured to slidably support the control member 310 in the sleeve. The sleeve 320comprises a main groove 325 extending in the extension direction of the sleeve(indicated by arrow E in Figure 3). The control member 310 comprises aguiding pin 315 arranged to be guided by the main groove 325 in the elongationdirection of the sleeve. The control member 310 can be pulled out from thesleeve whereby the guiding pin 315 traverses along the main groove 325. Bypulling on the control member 310, the tensile engagement member 340 actson the throttle actuator 340 and thus the engine speed is increased from theidle speed. The primary extension spring strives to pull the control memberback into the sleeve 320, i.e., back towards the idle position. lf the operatorlets go of the control member 310, the control member automatically revertsback to the idle position. This way prolonged operation in the undesired enginespeed range is avoided, since the operator needs to hold on to the controlmember since otherwise it reverts back to the idle throttle position which islikely to be awkward and to result in an uncomfortable working position. Thecontrol member 310 is also rotatably supported in the sleeve, which meansthat the guiding pin 315 can be moved transversal to the elongation directionE away from the main groove 325 and into one out of a plurality of lockingpositions 350, 360 via passages extending out transversally from the maingroove. Figure 3A and 3B show two distinct locking positions, one associatedwith a low speed 350 and one associated with a high speed 360. To select lowspeed operation, the control member is initially pulled out from the sleeve,where the guiding pin 315 travels along the main groove 325. The controlmember is then rotated clockwise such that the guiding pin enters the grooveformed parallel to and clockwise from the main groove via the passageextending out from the main groove. To select high speed operation, thecontrol member is instead rotated counter-clockwise such that the guiding pinenters the groove formed parallel to and counter-clockwise from the maingroove via the passage extending out from the main groove. Note that theparallel grooves forming the locking positions extend past the passagebetween the main groove and the respective parallel groove, forming ridges351, 361, such that the guiding pin 315 is held in position by the extension spring 380 if the control member is released when the guiding pin is receivedin one of the parallel grooves. ln other words, the ridges 351, 361 preventrotation of the control member once the guiding pin is in the locking position. ltis appreciated that the main groove and parallel grooves can be formed inmany different ways. Figure 3E schematically i||ustrates another groovearrangement with four different throttle positions selectable by the operator, inaddition to the idle throttle position 370.

According to some aspects, the biasing member also comprises a secondaryextension spring 385 configured to pull the control member 310 towards theidle throttle position. The secondary extension spring 385 is preferablyarranged with a higher spring constant compared to the primary extensionspring 380.

The purpose of the secondary extension spring 385 is to allow the guiding pinto traverse over the ridge 361 into the high speed throttle position, even if thethrottle actuator 330 has reached an end position. lt is appreciated that a Bowden cable or the like can be used as part of thetensile engagement member 340. However, unlike their use for switchinggears and controlling brakes on bicycles and the like, a pushing action by thetensile engagement member 340 is not necessary here. Hence, according tosome aspects, a more ﬂexible line or cord can be used instead of a stiff wire.Also, the line cord itself can be used to provide a level of resilience. Thus,according to some aspects, the tensile engagement member 340, 440, 540,640, 740 is at least partly made from a resilient material, thereby biasing thecontrol member towards the idle throttle position 370, 470, 770.

Figure 3B shows a cross-sectional view of the throttle control mechanism 300,taken along section A-A as indicated in Figure 3A.

Figure 3C i||ustrates details of the guiding pin 315. This example guiding pinalso serves the dual purpose of fixing the tensile engagement member 340 to the control member 310.

Figure 3D i||ustrates details of the secondary extension spring 385. As notedabove, this secondary extension spring is configured to generate a force which overcomes that generated by the primary extension spring 380. This way, asthe control member 310 is pulled all the way out of the support structure sleevesuch that the throttle actuator 330 contacts the end stop, the secondaryextension spring 385 still allows the guiding pin 315 to overtravel the ridge 361to the high speed locking position.

As an alternative or complement to the guiding pin and groove arrangementillustrated in Figures 3A-E, with reference to Figure 4, the cylindrically shapedcontrol member 410 may also comprise one or more circumferentially formedgrooves 455, 465 transversally formed with respect to an elongation directionE of the control member 410. The support structure 420 comprises a lockingpin 415 arranged biased B to enter the one or more circumferentially formedgrooves 455, 465, thereby fixing the control member 410 in at least the firstthrottle position 450, 460. This version of the control member 410 is also pulledout from the sleeve in order to increase engine speed via the tensileengagement member 440. However, holding the control member fixed in athrottle position is now achieved by the locking pin 415 which enters a groove,and thereby prevents the control member from sliding in the elongationdirection. The control member automatically reverts back to the idle throttleposition in case the locking pin 415 is released, i.e., is pulled up from thecircumferentially formed groove. The biasing force of the locking pin 415 maybe dimensioned such that a resolute push on the control member is enough tomove the control member out of a throttle position.

According to some aspects, a dead-man switch arrangement comprising a lineor cord 416 attached to the locking pin 415 is also provided. This line 416 can,e.g., be attached to an operator. lf this operator falls or is injured, then thedead-man switch is activated to bring the surfacing machine into the idlethrottle position. The dead-man switch can also be attached to, e.g., a vacuumdevice or other peripheral unit, thus ensuring that the peripheral unit is always near the surfacing machine.

The resilient biasing member may also comprise a compression spring whichprovides the technical effect of biasing the control member towards the idle throttle position. With reference to the examples shown in Figure 5 and Figure6, the biasing member comprises a compression spring 580, 680 configuredto push the control member 510, 610, 710 towards the idle throttle position.

The compression spring 580, 680, if present, is preferably comprised in thesupport structure 520, 620, 720. This way no springs or other resilientmembers need to be arranged in connection to the throttle actuator, or evenexternal to the support structure, which is an advantage.

Figure 5 i||ustrates one example where the compression spring 580 isarranged to resist pulling out the control member 510 from the supportstructure sleeve 520. lf the control member is released it reverts back to aposition retracted in the sleeve corresponding to the idle throttle position. Nolocking mechanism is shown in Figure 5, but it is appreciated that any lockingmechanism can be used, such as the guiding pin and groove lockingmechanism from Figures 3A-E or the locking pin mechanism from Figure 4.

Figure 6 instead shows a compression spring arrangement which resistspushing the control member into the support structure 620. The position wherethe control member extends fully from the support structure sleeve 620 nowcorresponds to the idle throttle position, while a control member fully pushedinto the sleeve corresponds to a position associated with high engine speed.Again, no locking mechanism is shown in Figure 6, but it is appreciated thatany locking mechanism can be used, such as the guiding pin and groovelocking mechanism from Figures 3A-E or the locking pin mechanism fromFigure 4.

Figure 7 i||ustrates aspects of the throttle control mechanism 700, wherein thecontrol member 710 comprises a handle 715 pivotably arranged in the supportstructure 720 instead of a control member configured to be pulled out from asleeve-like support structure. The handle is again biased towards a positionassociated with idle throttle. A torsion spring or the like may be used to biasthe control member towards the idle position. Alternatively, or in combinationwith the torsion spring, an extension spring may be used to bias the controlmember 710 towards to idle throttle position in a similar manner to the biasing member arrangement shown in Figures 3A-E. The control member 710 is hereheld in position by slots extending radially outwards from an annular maingroove 725, into which a pin 715 on the control member may enter viarespective passages from the main groove 725. The control member is biasedin the radial direction D, by, e.g., a compression spring or the like, in order forthe pin to strive to enter the slots, thereby holding the control member in adesired throttle position. As soon as the control member is pushed in directionopposite to direction D, the pin 715 again enters the main groove 725 where itautomatically travels to the idle throttle position 770 due to the biasing forceacting on the control member 710.

The tensile engagement member 740 is attached to the control member 710in a known manner. A Bowden cable or the like can be used as tensileengagement member 740 to connect the control member 710 to a throttleactuator arranged in connection to the combustion engine.

Claims

1. A throttle control mechanism (300, 400, 500, 600, 700) for a surfacingmachine (100), the control mechanism comprising a control member (310, 410, 510, 610, 710)arranged movable (M, D) in a support structure (320, 420, 520, 620, 720), wherein the control member (310, 410, 510, 610, 710) is arranged to be tenselyattached to a throttle actuator (330, 430, 530, 630) of the surfacing machine(100) via a tensile engagement member (340, 440, 540, 640, 740), wherein the control member (310, 410, 510, 610, 710) is arranged to be heldfixed in the support structure in at least a first throttle position (350, 450, 750),where the control member is arranged biased towards an idle throttle position(370, 470, 770) when released from the first throttle position (350, 450, 750), and wherein the first throttle position (350, 450, 750) and the idle throttle position(370, 470, 770) are configurable to provide an engine speed margin with respect to an undesired engine speed range of the surfacing machine (100).

2. The throttle control mechanism (300, 400, 500, 600, 700) according toclaim 1, wherein the control member (310, 410, 510, 610, 710) is arranged tobe held fixed in the support structure (320, 420, 520, 620, 720) at a secondthrottle position (360, 460, 760) different from the first throttle position (350,450, 750), wherein the second throttle position (360, 460, 760) is configurableto provide a further engine speed margin with respect to the undesired engine speed range.

3. The throttle control mechanism (300, 400, 500, 600, 700) according toany previous claim, comprising a resilient biasing member (380, 480, 580,680), wherein the control member (310, 410, 510, 610, 710) is arranged biasedtowards the idle throttle position (370, 470, 770) by the resilient biasing member.

4. The throttle control mechanism (300, 400) according to claim 3, whereinthe biasing member (380, 480) comprises a primary extension spring (380, 480) configured to pull the control member (310, 410) towards the idle throttleposition (370, 470).

5. The throttle control mechanism (300) according to claim 3 or 4, whereinthe resilient biasing member comprises a secondary extension spring (385)configured to pull the control member (310) towards the idle throttle position,wherein the secondary extension spring (385) is arranged with a higher springconstant compared to the primary extension spring (380).

6. The throttle control mechanism (300, 400, 500, 600, 700) according toany previous claim, wherein the tensile engagement member (340, 440, 540,640, 740) is at least partly made from a resilient material, thereby biasing thecontrol member towards the idle throttle position (370, 470, 770).

7. The throttle control mechanism (300) according to any previous claim,wherein the tensile engagement member (340) comprises an adjustmentscrew (342) configured to adjust a tension associated with the tensileengagement member (340).

8. The throttle control mechanism (300, 400, 500, 600) according to anyprevious claim, wherein the support structure (320, 420, 520, 620) comprisesa sleeve, and wherein the control member (310, 410, 510, 610) is arrangedinside the sleeve to slide along an extension direction (E) of the sleeve.

9. The throttle control mechanism (300) according to claim 8, wherein thesleeve comprises a slide bearing (376) configured to slidably support thecontrol member (310) inside the sleeve.

10. The throttle control mechanism (300) according to claim 8 or 9, whereinthe sleeve comprises a main groove (325) extending in the extension directionof the sleeve (E), and wherein the control member (310) comprises a guidingpin (315) arranged to be guided by the main groove (325) in the elongationdirection of the sleeve (E), wherein the control member (310) is rotatablysupported in the sleeve to move the guiding pin (315) transversal to theelongation direction (E) away from the main groove and into a locking position(350, 360).

11. The throttle control mechanism (400) according to claim 8 or 9, whereinthe control member (410) comprises one or more circumferentially formedgrooves (455, 465) transversally formed with respect to an elongation directionof the control member (E), and wherein the support structure (420) comprisesa locking pin (415) arranged biased (B) to enter the one or morecircumferentially formed grooves (455, 465), thereby fixing the control member(410) in at least the first throttle position (450, 460).

12. The throttle control mechanism (400) according to claim 11, comprisinga dead-man switch arrangement comprising a line or cord (416) attached tothe locking pin (415).

13. The throttle control mechanism (500, 600, 700) according to claim 3,wherein the resilient biasing member (580, 680) comprises a compressionspring configured to push the control member (510, 610, 710) towards the idlethrottle position.

14. The throttle control mechanism (500, 600, 700) according to claim 13,wherein the compression spring is comprised in the support structure (520,620, 720).

15. The throttle control mechanism (700) according to any of claims 1-3,wherein the control member (710) comprises a handle pivotably arranged inthe support structure (720).

16. A surfacing machine comprising the throttle control mechanism (300, 400,500, 600, 700) according to any previous claim.

17. The surfacing machine according to claim 16, wherein the first throttleposition (350, 450, 750) is a low speed throttle position configured to providean engine speed between 2800 rpm and 3200 rpm, and preferably 3000 rpm.

18. The surfacing machine according to claim 16 or 17, wherein the secondthrottle position (360, 460, 760) is a high speed throttle position configured toprovide an engine speed between 3300 rpm and 3700 rpm, and preferably3500 rpm.

19. The surfacing machine according to any of claims 16-18, wherein the surfacing machine is a floor grinding machine.

20. The surfacing machine according to c|aim 19, wherein the throttle controlmechanism (300, 400, 500, 600, 700) is configured to control a revolutionspeed of a planetary head and/or one or more satellites of the floor grinding machine.

21. The surfacing machine according to any of claims 16-20, comprising aclutch mechanism (220), wherein the clutch mechanism is a centrifugal clutch mechanism arranged to operate based on centrifugal force.

22. The surfacing machine according to any of c|aim 21, wherein theundesired engine speed range corresponds to a speed range from 90% of theclutch engagement speed to 110% of the clutch engagement speed.

23. The surfacing machine according to any of claims 16-22, comprising anengine (210), wherein the engine is a combustion engine, such as a propaneor gasoline fueled combustion engine.

24. A combustion engine powered lawn mover comprising the throttle controlmechanism (300, 400, 500, 600, 700) according to any of claims 1-15.

25. A combustion engine powered floor polishing machine comprising thethrottle control mechanism (300, 400, 500, 600, 700) according to any of claims1-15.

26. A combustion engine powered vacuum cleaner comprising the throttlecontrol mechanism (300, 400, 500, 600, 700) according to any of claims 1-15.

27. Combustion engine powered construction equipment comprising thethrottle control mechanism (300, 400, 500, 600, 700) according to any of claims1-15.

28. A method for operating a throttle control mechanism (300, 400, 500, 600,700) to control a machine powered by a combustion engine and comprising aclutch mechanism, the control mechanism comprising a control member (310,410, 510, 610, 710) arranged movable (M, D) in a support structure (320, 420,520, 620, 720), wherein the control member (310, 410, 510, 610, 710) is arranged to be tensely attached to a throttle actuator (330, 430, 530, 630) ofthe surfacing machine (100) via a tensile engagement member (340, 440, 540,640, 740), wherein the control member (310, 410, 510, 610, 710) is arrangedto be held fixed in the support structure in at least a first throttle position (350,450, 750), where the control member is arranged biased towards an idlethrottle position (370, 470, 770) when released from the first throttle position(350, 450, 750), and wherein the first throttle position (350, 450, 750) and theidle throttle position (370, 470, 770) are configurable to provide an enginespeed margin with respect to an undesired engine speed range ofthe surfacingmachine (100), the method comprising releasing the control member from a current throttle position, and moving the control member into a desired throttle position, whereby the control member is held fixed in the desired throttle position by the support structure.